At a meeting of the Des Moines Floral Association, March 4th, 1886, Mr. W. L. Morris read an essay on ventilation, wherein he set forth some of the errors in ventilating greenhouses. And one or two points were mentioned which may be of interest to some of the readers of the Gardeners' Monthly. Mr. Morris says, in the first place, many err in building a greenhouse, by putting in as few ventilators as they think will possibly do, when they should put in all they possibly could use. But they should be small and as near the ridge as possible, so that when opened the cold air coming in would have as much chance as possible to become diffused and warm before it strikes the plants, for I think a cold draught or sudden change, as harmful to plant as animal life, although they may not show it so plainly. And many who are opposed to steam, are ventilating in a manner that causes more sudden changes than steam heating. They do this by having their vents so large or so few of them, that in order to get the needed amount of fresh air, they must make so large an opening that the cold air rushing in to fill the vacuum left by the warm air passing out, comes in in such volume that it injures the plant by a draught or chill.

But with the fact before us, that cold seeks the lowest level, and heat the highest, I think we should have vents to introduce fresh air at the floor. Thus, the warm air would pass out above, and the cold air will remain near the floor until it gets warm enough to rise. And so we would have no cold air strike the plants; no strong draught, but a gentle circulation through the entire house. I think every greenhouse should have Hitchings' or some other ventilating apparatus, whereby an entire line of vents can be raised or lowered in a second, by the turn of a crank. Thus more attention can be given in changeable weather, and less time and labor required, than by the old way of a separate rod to each sash.

Quite an interesting discussion followed the reading of this essay, and more particularly in regard to the floor ventilators. We should like to hear from others on the subject.